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Fundamental Concepts of Database Management

7 important questions on Fundamental Concepts of Database Management

What type of databse system architectures?

Centralized
- all responsibilities of the DBMS are handled by one centralized entity
- nowadays this is rare, expensive and difficult to maintain

Tiered system architectures
- aimed to decouple the centralized setup

'Fat' client variant
- the presentation logic and application logic handled by client
- DBMS now fully runs on the database server

'Thin' client variant
- only presentation logic handled by client
- application and database commands both on server
- common when application and database logic are tightly coupled or similar

Also possible to decouple application from the DBMS and make it a seperate layer

What are database APIs?

Client applications that wish to utilize the services provided by a DBMS use a specific application programming interface (API) provided by the DBMS. This exposes an interface through which client applications can access and query a DBMS

The server receives calls made by clients and executes and returns results. This interaction is APIs main goals, but can also server additional objectives

Difference proprietary and universal APIs?

Proprietary
- disadvantage is that client applications must be aware of the DBMS that will be utilized on the server side

Universal
- allows easily porting of applications to multiple DBMS

Difference embedded and call-level?

An embedded API embeds SQL statements in the host programming language, meaning that SQL statements will be part of the source code.

Advantages
- pre compiler can perform specific syntax checks
- pre compiler can also perform an early binding step which helps to generate an efficient query plan before the program is run, hence improving performance
Disadvantage
- harder to maintain code
- are not very popular

Call level APIs work by passing SQL instructions to the DBMS by means of direct calls to a series of procedures, functions, or methods as provided by the API to perform the necessary actions

What are OLE DB and ADO?

Object linking and embedding for databases: was a follow up specification to ODBC to allow uniform access to a variety of data sources using Microsofts component object model (COM). Also supports object databases, spreadsheets and other data sources. Can be combined with ActiveX Data Objects (ADOs) which provides a richer more programmer friendly programming model on top of OLE DB
Combined into ADO.net which breaks down all database-related access features into a set of components

JDBC driver manager?

Is a singleton object which acts as the basic service to manage JDBC drivers. Can be created using one of the registered drivers.

Many drivers will also register themselves automatically. The driver objects registered with the drivermanager implement the driver interface and enable the communication between the driver manager the DBMS. To implement the interace, database vendors can decide between different so-called driver 'types'

What is language integrated querying?

A key JDBC drawback is the lack of compile time type checking and validation. Modern programming languages use language native query expressions into their syntax, which are often able to operate on any collection of data.
Example is: jOOQ

Since now only pure java code is used to express statements, IDEs do not need to be aware of a separate language, no pre compiler is necessary, and the standard java compiler can be used to perform type safety checks and generate compilation errors when necessary